'th' as a digraph

[sarah b]

ok really random question. can any1 giv me the exact date that the 'th' digraph entered the English spelling system? In what period of English did it replace thorn? Would also be good to know when any of the other later added graphemes, such as 'j' entered the alphabet. thanks

[Anglika]

No "exact" date is possible, but around the time that printing came into use for "th"; "j" came in a bit later, in the late 16th century.

Check out Wikipedia for more information on both.